Interpretive Summary: This research demonstrates that pyrolysis oil can be stabilized and upgraded using a simple catalyst system. Pyrolysis oil is a third generation biofuel that can be prepared from forestry and agricultural residues or energy crops. However, the oil suffers from instability due to high acidity. By converting the acids in the pyrolysis oil to neutral compounds, the instability issue is mitigated. This approach allows for the broader use of pyrolysis oil as a fuel supply, since the oil could be prepared at the farm and then shipped to a centralized refinery

Technical Abstract:
The stabilization and upgrading of pyrolysis oil requires the neutralization of the acidic components of the oil. The conversion of small organic acids, particularly acetic acid, to ketones is one approach to addressing the instability of the oils caused by low pH. In the ketonization reaction, acetic acid is converted to acetone, water, and CO2. Here, a 16 volume percent acetic acid solution is converted to acetone in a flow reactor over the composite oxide Fe0.2Ce0.2Al0.6Ox in the presence of several other components meant to represent pyrolysis oil. These components include acetol, furfural, phenol, cresol, guaiacol, and eugenol. Acetol also undergoes ketonization forming acetone, 2-butanone, 2-, and 3-hexanone, and 3-methyl-2-cyclohexene-1-one. A mechanism for the ketonization of acetol through propanal is proposed and supported by incorporation of isotope-labeled water. Inhibition of the reaction occurs to a significant degree by the addition of furfural, guaiacol, and eugenol.